<?php
/*************************************************************
# 076 License

Copyright (c) テクニカル諏訪子

Permission is hereby granted to any person obtaining a copy of the software
Little Beast (the "Software") to use, modify, merge, copy, publish, distribute,
sublicense, and/or sell copies of the Software, subject to the following conditions:

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         you created the original Software.
       - If the Software is used in a product, you must either:
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            or other visible areas, **OR**
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         incorporating it, must not be used for censorship or to suppress freedom of
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           ideas, or objective reality.
         - Tools or systems designed to restrict access to information or
           artistic works.
    3. **Notice Preservation**:
       - This license and the above copyright notice must remain intact in all copies
         of the source code.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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 */
namespace Std\Lib\Db\Sqlite;

use Std\Lib\Db\DbException;

/**
 * データベースのスキーマ（sqlite_schemaのテーブル・インデックス・ビュー）
 */
final class Schema {
  /** 小文字の名前 => テーブル */
  public array $tables = [];
  /** 小文字の名前 => インデックス */
  public array $indexes = [];
  /** 小文字の名前 => ビュー（name、sel、cols） */
  public array $views = [];
  /** トリガーの有るテーブル（小文字） */
  public array $triggers = [];
  public int $maxRowid = 0;

  /**
   * sqlite_schemaを読む
   */
  public static function load(Btree $bt, int $pages): self {
    $s = new self();
    $s->tables['sqlite_schema'] = self::schemaTable();
    if ($pages === 0) return $s;
    $parser = new Parser();
    $autos = [];
    foreach ($bt->scan(1) as $rowid => $rec) {
      $s->maxRowid = max($s->maxRowid, $rowid);
      [$type, $name, $tbl, $root, $sql] = Record::decode($rec) + [null, null, null, null, null];
      $type = (string)$type;
      $lname = strtolower((string)$name);
      try {
        if ($type === 'table') {
          $st = $parser->parseAll((string)$sql)[0] ?? null;
          if (($st['t'] ?? '') !== 'createTable' || !isset($st['def'])) throw new DbException("不正なテーブルのSQL：{$name}", 11, 'HY000');
          $s->tables[$lname] = self::table((string)$name, (int)$root, (string)$sql, $st['def']) + ['schemaRowid' => $rowid];
        } else if ($type === 'index') {
          if ($sql === null) {
            $autos[] = [(string)$name, strtolower((string)$tbl), (int)$root, $rowid];
            continue;
          }
          $st = $parser->parseAll((string)$sql)[0] ?? null;
          if (($st['t'] ?? '') !== 'createIndex') throw new DbException("不正なインデックスのSQL：{$name}", 11, 'HY000');
          $s->indexes[$lname] = ['name' => (string)$name, 'root' => (int)$root, 'table' => strtolower((string)$tbl), 'unique' => $st['unique'],
                                 'def' => $st['cols'], 'origin' => 'c', 'sql' => (string)$sql, 'schemaRowid' => $rowid];
        } else if ($type === 'view') {
          $st = $parser->parseAll((string)$sql)[0] ?? null;
          if (($st['t'] ?? '') !== 'createView') throw new DbException("不正なビューのSQL：{$name}", 11, 'HY000');
          $s->views[$lname] = ['name' => (string)$name, 'sel' => $st['sel'], 'cols' => $st['cols'], 'sql' => (string)$sql, 'schemaRowid' => $rowid];
        } else if ($type === 'trigger') {
          $s->triggers[strtolower((string)$tbl)] = true;
          $s->triggers['@'.$lname] = $rowid;
        }
      } catch (DbException $e) {
        if ($type === 'table' && str_contains($e->getMessage(), '未対応')) {
          // WITHOUT ROWID等：読めないテーブルとして
          $s->tables[$lname] = ['name' => (string)$name, 'unsupported' => $e->getMessage(), 'root' => (int)$root, 'cols' => [], 'map' => [],
                                'indexes' => [], 'schemaRowid' => $rowid, 'sql' => (string)$sql];
          continue;
        }
        throw $e;
      }
    }

    // 自動のインデックス（UNIQUE・PRIMARY KEYの制約）
    foreach ($autos as [$name, $tbl, $root, $rowid]) {
      $t = $s->tables[$tbl] ?? null;
      if (!$t || !preg_match('/_(\d+)$/', $name, $m)) continue;
      $c = $t['constraints'][(int)$m[1] - 1] ?? null;
      if ($c === null) throw new DbException("データベースが壊れています（{$name}）", 11, 'HY000');
      $s->indexes[strtolower($name)] = ['name' => $name, 'root' => $root, 'table' => $tbl, 'unique' => true, 'def' => $c[1],
                                        'origin' => $c[0] === 'pk' ? 'pk' : 'u', 'sql' => null, 'schemaRowid' => $rowid];
    }
    foreach ($s->indexes as $k => $idx) {
      if (!isset($s->tables[$idx['table']])) continue;
      $s->indexes[$k] = self::indexInfo($idx, $s->tables[$idx['table']]);
      $s->tables[$idx['table']]['indexes'][] = $k;
    }
    return $s;
  }

  /** sqlite_schemaのテーブル */
  private static function schemaTable(): array {
    $cols = [];
    foreach (['type' => 'text', 'name' => 'text', 'tbl_name' => 'text', 'rootpage' => 'int', 'sql' => 'text'] as $n => $ty) {
      $cols[] = ['name' => $n, 'type' => $ty, 'aff' => Value::affinity($ty), 'notNull' => false, 'default' => null, 'defaultText' => null,
                 'collate' => 'BINARY', 'pk' => 0];
    }
    return ['name' => 'sqlite_schema', 'root' => 1, 'sql' => '', 'cols' => $cols, 'map' => ['type' => 0, 'name' => 1, 'tbl_name' => 2, 'rootpage' => 3, 'sql' => 4],
            'ipk' => null, 'autoinc' => false, 'checks' => [], 'indexes' => [], 'constraints' => [], 'system' => true];
  }

  /**
   * テーブルの定義を作る
   *
   * @param array $def  Parser::tableBody()の結果
   */
  public static function table(string $name, int $root, string $sql, array $def): array {
    if ($def['withoutRowid']) throw new DbException("WITHOUT ROWIDのテーブルは未対応です：{$name}", 1, 'HY000');
    $cols = [];
    $map = [];
    foreach ($def['cols'] as $i => $c) {
      $lc = strtolower($c['name']);
      if (isset($map[$lc])) throw new DbException("重複した列：{$c['name']}", 1, 'HY000');
      $map[$lc] = $i;
      $cols[] = ['name' => $c['name'], 'type' => $c['type'], 'aff' => Value::affinity($c['type']), 'notNull' => $c['notNull'],
                 'default' => $c['default'], 'defaultText' => $c['defaultText'], 'collate' => $c['collate'] ?? 'BINARY', 'pk' => 0,
                 'checks' => $c['checks']];
    }
    $ipk = null;
    $pkCols = [];
    if ($def['pk'] !== null) {
      foreach ($def['pk'] as $k => $p) {
        $ci = $map[strtolower($p['name'])] ?? null;
        if ($ci === null) throw new DbException("主キーの列がありません：{$p['name']}", 1, 'HY000');
        $cols[$ci]['pk'] = $k + 1;
        $pkCols[] = $ci;
      }
      if (count($pkCols) === 1 && strtoupper($cols[$pkCols[0]]['type']) === 'INTEGER') {
        // 列の「INTEGER PRIMARY KEY DESC」だけはrowidの別名にならない
        $colDesc = false;
        foreach ($def['cols'] as $c) if ($c['pk'] && $c['pkDesc']) $colDesc = true;
        if (!$colDesc) $ipk = $pkCols[0];
      }
    }
    if ($def['pkAuto'] && $ipk === null) throw new DbException('AUTOINCREMENTはINTEGER PRIMARY KEYだけに使えます', 1, 'HY000');

    // 自動のインデックスの元になる制約（重複は1つ）
    $constraints = [];
    $seen = [];
    foreach ($def['order'] as [$kind, $list]) {
      if ($kind === 'pk' && $ipk !== null) continue;
      $key = implode(',', array_map(fn($p) => strtolower($p['name']), $list));
      if (isset($seen[$key])) continue;
      $seen[$key] = true;
      $constraints[] = [$kind, $list];
    }
    $checks = $def['checks'];
    foreach ($cols as $c) foreach ($c['checks'] as $ch) $checks[] = $ch;
    return ['name' => $name, 'root' => $root, 'sql' => $sql, 'cols' => $cols, 'map' => $map, 'ipk' => $ipk, 'autoinc' => $def['pkAuto'],
            'checks' => $checks, 'indexes' => [], 'constraints' => $constraints];
  }

  /** インデックスの列・照合順序・降順 */
  public static function indexInfo(array $idx, array $t): array {
    $cols = $colls = $desc = [];
    foreach ($idx['def'] as $d) {
      $ci = $t['map'][strtolower($d['name'])] ?? null;
      if ($ci === null) {
        if (in_array(strtolower($d['name']), ['rowid', 'oid', '_rowid_'], true)) throw new DbException('rowidのインデックスは未対応です', 1, 'HY000');
        throw new DbException("インデックスの列がありません：{$d['name']}", 1, 'HY000');
      }
      $cols[] = $ci;
      $colls[] = $d['collate'] ?? $t['cols'][$ci]['collate'];
      $desc[] = $d['desc'];
    }
    $colls[] = 'BINARY';
    $desc[] = false;
    return $idx + ['cols' => $cols, 'colls' => $colls, 'desc' => $desc];
  }

  /** テーブル（無ければnull） */
  public function table_(string $name): ?array {
    $l = strtolower($name);
    if ($l === 'sqlite_master' || $l === 'sqlite_temp_master' || $l === 'sqlite_temp_schema') $l = 'sqlite_schema';
    return $this->tables[$l] ?? null;
  }

  /** 名前が使われているか */
  public function exists(string $name): bool {
    $l = strtolower($name);
    return isset($this->tables[$l]) || isset($this->indexes[$l]) || isset($this->views[$l]) || isset($this->triggers['@'.$l])
      || $l === 'sqlite_master';
  }
}